One well known semiconductor processing step involves dicing a semiconductor wafer into singulated components. Typically the wafer includes a plurality of semiconductor dice or semiconductor packages, which are referred to herein as “semiconductor components”.
One technique for dicing a wafer is saw cutting. With saw cutting, the wafer is mounted to a support member, and a diamond tipped saw rotating at high rpms saws the wafer along pre-formed lines known as streets. Another technique for dicing a wafer is scribing. With scribing, the wafer is again mounted to a support member, scribed along the streets, and then broken along the scribe lines by application of pressure exerted through a roller or other mechanism.
One conventional support member for dicing a wafer is known as a film frame. The film frame includes a metal frame, and an adhesive dicing tape stretched across the metal frame. The dicing tape can comprise a polymer film having an adhesive on one or both sides or a polymer layer having adhesive qualities. The dicing tape is formulated to provide a high adhesion with the wafer in order to prevent the wafer, and the singulated components, from moving during the dicing process. The high adhesion of the dicing tape is also advantageous for transporting the singulated components on the film frame for further processing, such as packaging.
However, the high adhesion of the dicing tape is a disadvantage when the singulated components must be removed from the tape. For example, mechanisms such as pushers and vacuum picks are utilized to either push or pull the singulated components from the dicing tape. These mechanisms are hampered by the high adhesion of the dicing tape, which must be overcome to separate the singulated components from the tape.
One prior art approach for reducing the adhesion of the dicing tape, is to construct the tape using an adhesive that is sensitive to a radiation, such as ultraviolet radiation. With a radiation sensitive dicing tape, exposure of the back side of the tape to the radiation reduces the adhesion of the tape, allowing the singulated components to be more easily separated from the tape. Typically, the entire backside of the dicing tape is exposed to the radiation, and adhesion of the tape can be reduced by a factor of ten or more.
One shortcoming of this approach is that not all of the singulated components are removed from the dicing tape at the same time. For example, semiconductor components are often graded according to speed, and the premium components are utilized in some products, while the non-premium components are utilized in other products. The premium components may thus be removed from the dicing tape for processing prior to the non-premium components (or vice versa). However, if all of the dicing tape has been exposed to radiation, the non-premium components remaining on the tape may not be secured for further transport. Accordingly, these components can move, or separate entirely from the dicing tape. This movement and separation can chip and damage the dice and cause problems in handling and in subsequent processing steps.
Another prior art approach for processing singulated components is disclosed in U.S. Pat. No. 6,140,151 to Akram. This approach involves exposing only selected portions of the dicing tape to radiation. For example, the selected portions can be adjacent to the premium components, permitting these components to be easily removed, while the non-premium components remain attached to the tape. With this technique a mask and a wafer stepper can be used to expose only selected portions of the dicing tape. One shortcoming of this technique is that additional equipment (e.g. mask, stepper), and an additional process step are required to expose the dicing tape.
The present invention is directed to a method and system for attaching semiconductor components to substrates, in which radiation curing of the dicing tape is incorporated into a component attach process. In addition, the present invention incorporates a radiation curing system into the component attach system, and performs the curing step simultaneously with a component attach step.